Question

I am taking the liberty to write to you because of a management dilemma which Iam having difficulty to solve using the available published data.A 34-year-old womanwas referred to ourInstitutionafter she had undergonetotal thyroidectomy andright modified neck dissection.The surgery was performed because FNAof a lateral neck mass (presumed to be a lymph node) revealed thyroid tissue. The pathology of the thyroid glandconsisted ofnodular Hashimoto's thyroiditis with no evidence for neoplasia. 12 lymph nodes were excised, 11 ofwhich were normal or "reactive". The remaining mass, the one that has been originally biopsied (region 2 of the neck, next to the jugular vein), initially was interpreted as "thyroid inclusion in lymph node" , thefollicular cells appeared normal.The slides were re-examined in the pathology department of our institution and their conclusion was thatthe lesionis a "parasitic thyroid nodule, in the context of Hashimoto's thyroiditis". They explained to me that the whole mass looked like Hashimoto, and did not fit the diagnosis of inclusion, whereone should be able to identify normal lymph node structure, with a small subcapsular area ofthyroid tissue. Looking through the literature, I was not able to makeup my mind as to whether these lesions should be considered potentially as metastasisfrom well differentiated thyroid carcinoma, and thus be treated accordingly (we usuallyadminister 150 mCu I131 incases of metastasis to lymph nodes) or interpret it and treat it as a benign finding. What is your position? I thank you very much for your time.

Sincerely,

Yona Greenman MD
Tel Aviv-Sourasky Medical Center, Tel Aviv

Response

My understanding is that the idea of "lateral aberrant thyroid" has been largely laid to rest, and thyroid tissue outside the thyroid or in a node is now generally thought to be a met. Obviously this is difficult to prove. It is not hard to imagine that thyroiditis could involve the aberrant tissue as well as the thyroid. Inability to find a primary in a patient with a nodal met is always distressing, but not rare. Thus I feel, with no published support that I am aware of, that the case is best handled as if the process was a low grade tumor with a met, and would agree with 131-I ablation. I think I would use a somewhat lower dose.

It would be of great interest to hear from others who read this case if they have reason for a different approach. Best regards.

L De Groot, MD

Addendum 2/28/06

I would like to give you an update on the thyroid carcinoma case that you've so kindly advised us recently. We've prepared additional slides from both the thyroid and the lymphnodeand submitted it for a third opinion. In the new preparates from the lymphnodes an area with characteristic papillary carcinomacells was identified, but no primary focus was found in the thyroid gland. We decided to treat it as customary for metastatic papillary CA to lymphnodes i.e. 150 mCu I131.